update travis config for varint/no-varint builds

and don't try to build a C ext in jruby builds

Author: codekitchen

.travis.yml

@@ -1,11 +1,19 @@
 language: ruby
+gemfile:
+  - Gemfile
+  # i can't find a way to use the same Gemfile and just specify --without varint
+  - Gemfile.no_varint
 rvm:
   - "1.8.7"
   - "1.9.3"
   - jruby-18mode # JRuby in 1.8 mode
   - jruby-19mode # JRuby in 1.9 mode
   - rbx-18mode
   - rbx-19mode
-# uncomment this line if your project needs to run something other than `rake`:
-# script: bundle exec rspec spec
-
+matrix:
+  exclude:
+    # can't use the varint extension in jruby runs
+    - rvm: jruby-18mode
+      gemfile: Gemfile
+    - rvm: jruby-19mode
+      gemfile: Gemfile

Gemfile.no_varint

@@ -0,0 +1,4 @@
+source "https://rubygems.org"
+
+# Specify your gem's dependencies in ruby-protocol-buffers.gemspec
+gemspec